To best understand where western alienation comes from you have to actually live in western Canada. IMO, its not ASB to have several west Canadian provinces break away/attempt to break away in the face of an economic crisis. Remember this is before the Clarity Bill, so it is possible; it would simply be a re-run of Hitler's rise to power, only more along the Quebec secession lines. I never said Meech Lake was the POD as well, it was simply an example to show where I was coming from with choosing a POD after 1900.
It would not be hard to turn moderates to the pro-secession side if the standards of living go WAY down. My idea for a POD is the National Energy Program). Say the global oil prices drop faster and greater than IOTL and Trudeau also puts larger taxes onto the oil collected in Alberta, further reducing the provincial and private revenue. Say he also goes off the beaten trail and decides to buy out several foreign oil companies within the first year of the plan to help meet the NEP goals by borrowing cash from abroad (increasing Canadian debt with further impacts on inflation). All of this would create an almost depression-like state in the oil producing provinces (Alberta, Saskatchewan and to some extent BC), and no relief would be forthcoming since the federal government does not act--until Ontario and Quebec start feeling the signs of a recession when the anticipated oil money does not arrive. No help would create the perfect breeding ground for a radical movement, and with the provincial government not able to do much it would not be too hard to see such a party get voted into power after a few years. Assuming Trudeau does not disband the NEP either, there would be almost no relief for Alberta and such until oil prices begin to rise steadily in the mid 1990's.